Canon SD1400 IS has a
14.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features Digic 4 processor. On the other hand, Canon SD940 IS has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features Digic 4 processor.
Below you can see the SD1400 IS and SD940 IS sensor size comparison.
Canon SD1400 IS and Canon SD940 IS have the same sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture.